(1)Field of the Invention
The present invention relates to the use of vegetable oils in environmentally sound applications as a total replacement for current petroleum and vegetable-based additives to petroleum. Its use in applications to internal combustion engines provides not only acceptable biodegradability but superior lubricity to petroleum lubricants. In total loss applications, such as rail oils and chain oils, it provides superior lubricity, heat transfer and rapid degradation after disposal desired by users.
(2)Description of the Related Art
The principal use of motor oils is to prevent metal-to-metal contact between moving engine parts with respect to heat and friction. In the absence of a lubricant, friction caused by the rubbing of the moving parts creates heat. Heat then acts to weld tiny imperfections in the moving parts together. The welds then tear and re-weld themselves. This process, referred to as "scuffing", if allowed to continue, will cause engine failure.
Motor oils prevent the metal-to-metal contact by forming a film between moving parts. In addition to reducing friction between moving parts, the lubricant also functions as a coolant for the parts, a corrosion preventative and as a sealant for engine rings.
Total loss applications are quite similar to motor oils. The difference being that total loss oils are used once, briefly, and then are discarded in the proximate environment. Examples of total loss applications include rail oils for trains, bar/chain oils for wood cutting and metal cutting oils. The immediate consumption of total loss oils is relatively insignificant but the cumulative effect is dramatic. A train alone may consume 5 gallons of oil per 1,000 miles as the oil is sprayed on the track to lubricate the wheels. This amounts to a total of 300,000 gallons annually being discarded along railings within the U.S. alone.
Traditionally, mineral oils, produced from petroleum, have been the primary source of engine lubricants, as well as total loss application. The petroleum oils are composed primarily of hydrocarbons in nature and therefore lack chemical functionality. These petroleum oils are structurally composed of naphthenic, parafinic or aromatic structures.
Naphthenic structures have common, general characteristics: they have low viscosity, good pour points and poor oxidative stability. Paraffinic structures also have common characteristics: they have higher viscosity, high pour points and good oxidative stability. Aromatic structures generally have very high viscosity, variable pour points and poor oxidative stability.
Lubricants are made by distilling and refining crude petroleum. A host of various chemicals are added to this petroleum base to improve their physical properties and performances. As an example, various polymeric substances are added to the base oil to improve viscosity and act as a dispersant. Micronized polytetraflouroethylene (PTFE) is added to provide lubricity and reduce engine wear. Various amines, metal phenates and zinc salts are added as antioxidants.
In some formulations, notably the "synthetic oil" or "blended synthetic oil" formulations, additional micronized nylons or modified vegetable oils are added for additional lubricity and thermal stability. Finally, alkaline-earth phenates are added to neutralize acids and reduce wear.
Petroleum based lubricants suffer from a number of drawbacks. The crude petroleum from which they are derived is a nonrenewable resource. The world oil reserves are, if current consumption levels continue, expected to be exhausted within 40 years. Additionally, petroleum based motor oils are highly toxic to the environment and are hazardous to both the flora and fauna. Recent studies indicate these oils are carcinogenic and they are classified as a hazardous waste. Finally, petroleum based oils, with their chemical additives are not readily degraded in the environment. As a result, they persist for long periods in an ecosystem. The ecological problems associated with the refining and disposal of petroleum products are well known.
A second group of available lubricants are the synthetic oils. Synthetic oils have been developed to obtain intrinsic qualities such as lubricity and thermal stability. They are frequently designed for use in extreme conditions such as extreme temperature, vacuum, radiation or chemical environments. The most common synthetic lubricants are silicones, polyglycols, phosphate esters, dibasic acid esters and silicate esters. Synthetic lubricants are relatively costly and also suffer from a multitude of drawbacks similar to those of petroleum. They are frequently toxic to the environment, hazardous to flora and fauna and are not readily biodegradable.
A third group are the fixed oils. Fixed oils are fatty substances derived from animals, plants and fish. They are called fixed oils since they will not volitilize without decomposing. Fixed oils are generally composed of fatty acids and alcohols, the radicals of which are joined to form fatty acid esters. These transesterified oils are frequently blended with petroleum to provide functionality to the petroleum and reduce cost since transesterification is an expensive process and a pure fixed oil product would not be commercially feasible. Although the fixed oils by themselves are biodegradable, once they are mixed with petroleum this is lost.
Consequently, there is a strong need for an effective motor oil which can lubricate moving metal parts in internal combustion engines, which is derived from a renewable resource, is non-toxic to the environment and is readily biodegradable, preferably by microbes naturally present in the environment. The oil should also be cost effective to produce and market. It should also be usable in total loss applications.
Prior teachings in applications of vegetable oils for lubrication have been focused on the use of these oils as additives to a petroleum base oil. Prior teachings have emphasized that vegetable oils are functional as additives in petroleum lubricants for engines and transmissions. Their enhanced lubricity has significantly improved the efficacy of petroleum but they are rarely used at percentages exceeding 20 percent of the composition by volume of the final lubricant. Other applications primarily use a transesterified vegetable oil, converting the glycerols to a free fatty acid form prior to use.